1. Field
Embodiments of the present invention relate to a semiconductor integrated circuit apparatus including a power-controlling unit that controls power for a plurality of power domains.
2. Description of Related Art
A semiconductor integrated circuit (“IC”), e.g., a LSI IC, VLSI IC, etc., may incorporate a plurality of circuit macros (or IP macros or proprietary macros), where the term “macro” designates a circuit arranged for a particular function. Furthermore, such an IC may be provided with a plurality of power domains (power areas) to save power consumption, and a power-controlling unit to power-control a plurality of the circuit macros belonging to the different power domains. It is not necessary for all the circuit macros to be energized at all times. Power can be saved by selectively turning on/off power to the power domain to which a given circuit macro(s) belongs, according to a condition of a requested process.
Methods which control the supply of power to a circuit macro in a system LSI are described in Japanese laid open No. 2006-107127 and Japanese laid open No. 2006-237189.
In Japanese laid open No. 2006-107127, the power-controlling unit in the system LSI responds to an external interrupt signal to read a command sequence stored in a memory. Next, the power-controlling unit causes a power IC to control the activation of a power circuit of the circuit macro in the system LSI. Thereby, the power-controlling unit can supply the power only to the power area which needs to operate.
In Japanese laid open No. 2006-237189, the power-controlling unit in the system LSI includes a power control register storing a bit for controlling to supply and block the power for each IP macro. An interrupt controller responds to an interrupt from the IP macro to output a power control signal to the power-controlling unit, and causes the power-controlling unit to control the power block to the IP macro according to a result of the comparison with the power control register. When the power is supplied, the interrupt controller outputs the power control signal to the power-controlling unit to cause the power-controlling unit to control the power supply to the IP macro.